Achieving high figure of merit (ZT) thermoelectric materials is a challenge because it requires a combination of low thermal conductivity κ and high thermoelectric power factor (α2σ), i.e., high electrical conductivity σ and Seebeck coefficient α, and these properties are often contraindicated. One approach to achieving high ZT thermoelectric materials is through nanostructuring, which has been shown to factorially increase ZT due to size-scattering induced decrease of thermal conductivity κ, yet possesses a high electrical conductivity σ and Seebeck coefficient α due to quantum effects.
Nanostructuring bismuth- and antimony-based chalcogenides and their alloys are of great interest because these materials exhibit the highest room temperature ZT of ˜1 in bulk. Restricting the characteristic dimensions of these bismuth and antimony based chalcogenides to below 10 nm offers the potential to obtaining further ZT increases. However, except for a surfactant-directed synthesis that achieves 2.5 to 10 nm diameter single crystal bismuth telluride particles, few techniques exist for synthesizing pnictogen chalcogenide nanocrystals with characteristic dimensions <10 nm. Bismuth and antimony chalcogenide nanostructures synthesized by solvothermal routes or by electrodeposition into inorganic templates often produce polycrystalline or polydisperse products instead of single crystals with controllable sizes and shapes, and involve long times, ranging from a few hours to a couple of days, for formation.
Thus, there continues to be a need in the art for materials and methods for producing high quality single crystal bismuth- and antimony-based chalcogenide nanoparticles.